The externally insulated finishing systems (hereinafter referred to as EIFS) construction basically consists of framing a building and covering the outside surface with a backboard that may be plywood, gypsum or cement board prior to attaching the exterior insulation and finish.
The exterior insulation consists of EPS sheets mechanically or adhesively attached to the backboard. The EPS sheets are then covered with one or two layers of cloth mesh and a base coat of stucco.
The base coat is either sprayed or trowelled on and finished smooth by hand with a float. A finish stucco material is then applied to give the desired decorative surface and colour.
Decorative mouldings are generally preformed and finished and are ready to be installed on the construction site. They are typically comprised of an expanded polystyrene (EPS) core and coated with a plaster or stucco-like material to provide an attractive decorative finished surface. To improve strength and durability, a fibre mesh can be applied to the core prior to coating.
The prevalent method of producing a decorative moulding is to align rows of the cores on plastic topped tables and staple or screw them to the tabletop. There could be as many as four rows of cores places side by side on a four feet wide table, extending up to ninety feet long or more. If required, the cores may have had mesh applied prior to placing them on the table.
The coating material is poured from a pail along the length of the cores and massaged by hand on to the exposed surfaces of the cores. A box, with a steel template cut to a finish profile, is then slid along the length of the table, thus imparting the finished profile on the workpiece. The workpiece is allowed to dry, and another coating can be applied with a finer grained material to impart a smoother finish.
After allowing the workpiece to completely dry, it is pried off the table. The edges that were defined by the tabletop can be sanded and any minor imperfections can be repaired.
This whole process usually takes twenty-four hours and requires clean up after of the tabletops, removal of the screws, cleaning the box and template. This method is very costly, in terms of labour and space.
More recently, various types of automated equipment have been produced to apply the coating. These basically involve pushing the pre-formed core through a coating chamber equipped with sides, bottom and entry and exit dies or templates. So far there has not been any manufacturer to offer a rationalized standard, off the shelf, range of templates or coating chamber/hopper to accommodate such a selection. No manufacturer has been able to provide templates that are adjustable to allow for the inevitable variation of the pre-formed core sizes. For example Canadian patent 2,229,933 published Aug. 19, 1999 discloses a method and apparatus for coating a decorative workpiece. This apparatus drives a core through a coating chamber with a pair of conveyor belts with spikes penetrating the core from the bottom surface. The core is driven through a pressurized coating chamber by the conveyor belts. An elongate channel or dovetail is pre-cut in the bottom of the core that engages on a corresponding rail on the apparatus, and holds the core against lateral and vertical movement as it is coated. While this method and apparatus does provide a coating on the decorative surface of the workpiece, in practise it can be very troublesome. If the cores are not tightly placed end to end with each other as they pass through the coating chamber, the coating material leaks on to the conveyor belts and rail. The leaked material can accumulate as lumps on the belts and impart an uneven finish on the workpiece. Furthermore, as the last core passes through the coating chamber, all the excess material falls onto the rail and spiked belts thus requiring a meticulous cleanup.
Additionally, the apparatus disclosed in Canadian patent 2,229,933 published Aug. 19, 1999 is extremely limited in its application in coating decorative inside corner mouldings. Also, an undesirable channel or dovetail is required on the underside of the core. Furthermore, because the ends of the coating chamber are angled, the templates are not easily produced because of the complicated rendering of the resulting perpendicular section required on the workpiece. Also, no method is disclosed to adjust the coating thickness other than the fixed sizes of the templates.
Canadian patent application 2184205 discloses a method and apparatus for manufacturing decorative mouldings. In this method, the workpiece is driven by conveyor belts abutting both sides of the workpiece before passing through a coating chamber while being slidingly engaged with a continuous flat tabletop. While this apparatus does provide a coating on the decorative surface of the workpiece, it is also troublesome and limited in its application. Firstly, if the cores are not tightly butted up against each other, end to end, the coating material leaks on to the tabletop, accumulates and affects the thickness of the coating. Holding the cores against the tabletop as they pass through the coating chamber creates friction that makes the cores harder to drive through the coating chamber. For inside corner mouldings, the conveyor belts can only drive against two corners on the sides of the core. The belts rip the corners of the core before entering the coating chamber. Slipping can occur which results in an uneven surface finish. Pieces of the core are carried into the coating chamber and contaminate the mix. The dies as illustrated in the patent with tapered openings having sharp inside corners are not easily achieved, except by hand grinding and filing, making them too costly. Additionally, the apparatus does not allow for adjusting the coating thickness other than the fixed sizes of the templates.
Therefore, there is a need to develop a method and apparatus for coating the cored workpieces that includes a coating chamber that accepts a standard range of templates, templates that adjust to allow control of the coating thickness and for size variations of the cores, a way to allow material to escape if the cores are not butted close enough to prevent leakage between subsequent cores as they pass through the coating chamber.